THE  GENUS  ONGHOGOTYLE,  WITH  A 
DESCRIPTION  OF  ONGHOGOTYLE 
WARDI,  N.  SP. 


BY 

DAVID  CAUSEY 

A.B.  James  Millikin  University,  1921 


THESIS 


SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS 
FOR  THE  DEGREE  OF  MASTER  OF  ARTS  IN  ZOOLOGY 
IN  THE  GRADUATE  SCHOOL  OF  THE  UNIVERSITY 
OF  ILLINOIS,  1922 


URBANA,  ILLINOIS 


Et  H 


■ 


' 

. 


TABLE  OF  CONTENTS 


I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 


VIII. 

IX. 


Foreword  

Technique  

The  Genus  Onchocotyle  

The  Systematic  Position  of  the  Genus 

Onchocotyle  

Comparison  of  Onchocotyle  Ward!,  N.  Sp.,  with 

the  Other  Species  of  the  Genus  

Key  to  the  Species  of  the  Genus  Onchocotyle 
The  Morphology  of  Onchocotyle  Wardi,  N.  Sp. 

1.  The  General  Form  and  Size  

2.  The  Digestive  System  

3.  The  Excretory  System  

4.  The  Reproductive  System  

5.  The  Nervous  System  

Conclusions . 

Bibliography  

Explanation  of  Plat S3  


Page 

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15 

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IS 

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Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/genusonchocotyleOOcaus 


I . Foreword 


This  research  waa  undertaken  in  the  Laboratory  of 
Parasitology  at  the  University  of  Illinois,  under  the  direction 
of  Doctor  Henry  B.  Ward,  to  whom  the  writer  wishes  to  express 
his  sincere  appreciation  of  the  interest  shown  in  the  work,  and 
for  the  furnishing  of  the  material  which  made  it  possible.  The 
writer  also  acknowledges  many  helpful  suggestions  from  Mr.  D.  C. 
Hetherington . 

The  specimens  used  in  this  research  were  obtained 
from  the  gills  of  the  Sleeper  Shark,  Somniosus  microcephalus 
Block,  at  Excursion  Inlet,  Alaska,  on  July  26,  1S09.  The  Sleeper 
Shark  is  also  the  host  of  Onchocotyle  borealis,  the  species  most 
nearly  resembling  the  new  species.  It  i3  known  in  European 
waters  as  the  Greenland  Shark.  Gooae,  speaking  of  this  shark, 
says : 

"This  species,  also  called  by  our  fishermen  the  "Gurry" 
or  "Ground"  Shark,  is  a native  of  the  Arctic  Seas,  but  on  our 
coast  ranges  south  to  Cape  Cod,  and  in  the  Eastern  Atlantic  at 
least  to  England,  while  in  the  Pacific  it  has  been  observed  from 
Puget  Sound  northward." 


. 


. 


! ••  • 


- 


; 


-2- 


II.  Technique 

The  parasites  as  obtained  for  study  were  in  85$  alcohol, 
having  been  killed  with  corrosive  acetic  fixing  fluid.  The  excess 
of  corrosive  sublimate  was  removed  with  iodine  in  alcoholic  solu- 
tion in  the  usual  manner.  For  toto  preparations  the  worms  were 
over-stained  in  paracarmine  or  Delafield’s  haematoxylin,  and  then 
destained  in  acid  alcohol.  After  neutralization  with  alkaline 
alcohol  (NH4QH),  the  specimens  were  cleared  in  synthetic  oil  of 
winter green  and  mounted  in  balsam.  Xylol,  cedar  oil,  and  clove 
oil  were  tried  in  addition  to  the  oil  of  wintergreen,  but  the 
latter  gave  the  most  satisfactory  results.  The  worms  stain  in- 
tensely, and  best  differentiation  was  obtained  after  the  mounts 
were  finished  by  exposing  the  slides  to  sunlight.  This  brought 
about  a gradual  de staining  that  brought  out  the  reproductive  sys- 
tem in  a satisfactory  manner.  For  sections,  Delafield’s  haema- 
toxylin with  erythrosin  as  a counter-stain  gave  the  desired  con- 
trast. The  digestive  system  takes  the  stain  very  poorly,  the  dark 
granules  are  quite  unaffected,  which  is  also  the  case  of  the 
vitellaria.  In  both  cases,  the  natural  coloration  is  quite  suffi- 
cient. The  mesenchyma  and  reproductive  systems  take  the  stain 
readily . 

The  toto  preparations,  because  of  their  great  thickness, 
could  not  be  studied  to  any  extent  under  the  compound  microscope. 
Instead  a binocular  dissecting  microscope  was  used  and  served  the 
purpose  very  well. 


i 


-3- 

III.  The  Genus  Onohocotyle  Diesing  1850 

The  genus  Onohocotyle  was  first  established  by  Die3ing 
in  1850,  based  on  the  trematode  discovered  by  Kuhn  in  1829  and 
named  by  him  Poly stoma  appendiculatum.  This  is  now  Onohocotyle 
appendiculatum . The  genus  was  originally  described  by  Diesing 
as  follows: 

"Corpus  lineari  - lanceolatum  depressum,  utrinque 
angustatum.  Caput  corpore  continum.  O3  subterminale . Acetabula 
sex  disco  elliptico  extremitati  caudali  3upra  adnato,  bi seriatim 
immersa,  hemisphaerica,  margine  uncino  simplici  inferna  adnato 
apice  libero  armata.  Aperturae  genitales  . . . Porus  excretorius 
in  apice  caudali.  Piscium  marinorum  ectoparasita . " 

Goto's  definition  in  1894  is  as  follows: 

"Body  elongated,  very  thick,  narrow  towards  both  ends; 
anterior  end  blunt,  and  with  a sub-ellipsoidal  sucker  around  the 
mouth  cavity;  with  three  pairs  of  circular  or  elliptical  suckers 
at  the  posterior  end,  each  with  a semi-circular  chitinous  support- 
ing piece  with  one  of  the  ends  provided  with  a claw.  With  a sub- 
cylindrical  caudal  appendage,  which  bears  at  its  extremity  a pair 
of  small  suckers  destitute  of  any  chitinous  framework;  often  with 
a pair  of  hooks  between  these  suckers.  With  a paired  vaginal 
opening  on  the  ventral  side  of  the  body.  Porus  genitalis  ventral 
and  median . " 

The  following  species  have  been  described: 


- 


-4- 

Onchocotyls  abbreviata  Olsson  187S. 

" appendiculata  (Kuhn,  1830)  Diesing  1850. 

" borealis  van  Bensden  1853. 

" canis  (Cerf ontaine,  1899)  Pratt  1900. 

" emarginata  Olsson  1876. 

" scymni  ainosi  Diesing  1858. 

" spinacis  Goto  1894. 

" canicula  (Cerf ontaine,  1899). 

" vulgaris  (Cerf ontaine,  1899). 

H griesa  (Cerf ontaine,  1899). 

n batis  (Cerfontaine,  1899). 

" prenanti  St.  Remy  1890. 

" alba  (Cerfontaine,  1899). 

Of  these,  0.  emarginata  Olsson  1876  has  been  shown  to 
be  synonymous  with  0.  appendiculata.  0.  scymni  ainosi  was 
listed  by  Diesing  in  1858,  with  the  remark  that  there  was  no 
description  of  this  species.  Obviously  a named  species  without 
a description  cannot  be  given  serious  consideration. 


-5- 


IV.  The  Systematic  Position  of  the  Genu3  Onchocotyle 

The  systematic  position  of  the  genus  Onchocotyle  is 
quite  typical  for  so  many  genra  of  parasites  first  described  early 
in  the  last  century  and  hastily  assigned  systematic  positions 
without  careful  study.  Scarcely  an  investigator  ha3  worked  with 
this  genus  without  changing  the  nomenclature  and  systematic  posi- 
tion. 

The  first  species  of  this  genus  was  described  by  Kuhn 
in  1829  as  Poly stoma  appendiculatum.  Diesing  established  the 
genus  Onchocotyle  in  1850,  and  Polystoma  appendiculatum  became 
Onchocotyle  appendiculatum.  Van  Beneden  in  1853  described  a new 
species  of  the  Onchocotyle  which  he  had  found  on  the  gills  of 
Scimnus  glacialis  and  named  Onchocotyle  borealis,  a genus  of  the 
family  Polystomidae . The  systematic  position  was  clearly  shown 
by  him  in  1858  when  he  proposed  a classification  of  trematodes 
which  gained  general  acceptance  and  in  its  main  features  is  the 
one  recognized  today.  Van  Beneden  divided  the  order  of  trematodes 
into  two  sub-orders:  the  Monogenea.  which  develop  directly  with- 

out metamorphosis,  and  are  largely  ecto-para3i tic ; and  the  Dige- 
nea.  which  undergo  metamorphosis,  and  are  mainly  endoparasit ic . 

He  divided  the  sub-order  Monogenea  into  two  families:  the  Tristo- 

midae  being  forms  with  a single  posterior  sucker;  and  the  Polysto- 
midae. forms  with  two  or  more  posterior  suckers.  The  following 
is  adapted  from  his  paper  of  1858: 


■ 


, ; 


-6- 


Order 

Sub- order 

Family 

Genra 

Trematoda 

I . Monogenea 

I.  Tristomidae 

I.  Udonella 

II.  Epibdella 

III.  Tristoma 

II.  Polystomidae 

I.  Diplozoon 

II .Digenea 

In  1863  Van  Beneden  and  Hesse 
earlier  classification  as  follows: 

Order  Sub-order 

Trematodes  Monogenea  Tristomidae 

Polystomidae 
Octocotylidae 
Uronellidae 
Gy  r odac  t y 1 i dae 

Onchocotyle  was  retained  as  a genus  under  the  family 
Polystomidae  as  in  the  original  classification. 


II. 

Octobothrium 

III. 

Axine 

IV, 

Onchocotyle 

V. 

Polystomuin 

VI. 

Calceostoma 

VII. 

Gyrodactylus 

revised  and  expanded  the 


Fami ly 


-7- 

Monticelli  proposed  in  1392  a new  classification  of 
t remat odes  which  was  adopted  by  most  of  his  fellow  workers  with 
some  modification,  and  which  was  in  vogue  for  a number  of  years. 

He  discarded  the  older  division  into  the  Mono gene a and  Digenea, 
and  instead,  made  three  great  groups  or  sub-orders. 

Order  Sub- order 

I.  Trematoda  I.  Heterocotylea 

II.  Aspidocotylea 

III.  Malacotylea 

The  Heterocotylea  were  practically  the  same  a3  the  Monogenea, 
while  under  the  Aspidocotylea  and  Malacotylea  were  grouped  the 
members  of  the  Digenea.  The  Heterocotylea  were  subdivided  into  a 
large  number  of  families,  among  which  were  the  Polystomidae  and 
the  Ootocotylidae . The  Onohocotyle  were  taken  from  the  Polystomidae , 
and  placed  among  the  Ootocotylidae , the  sub-family  Qnchocotylinae 
being  created.  The  Qnchocotylinae  included  three  genera:  Squal- 

onchocotyle,  Onchocotyls , and  Raj  onohocotyle . 

It  is  interesting  to  note  that  in  the  same  year,  1893, 
Saint-Remy's  classification  not  only  was  based  on  that  of  van 
Beneden,  but  made  the  family  Polystomidae  include  both  the  Octoco- 
tylinae  and  the  Polystominae . The  Onohocotyle  were  placed  as  a 
genus  in  the  sub-family  Polystominae . His  classification  was: 


■ 


-3- 

Order  Sub-order  Family  Sub-family 

I.  Trematoda  I.  Monogenea  I.  Temnocephalidae 

II.  Triatomidae 

III.  Polystomidae 

I.  Octocotylinae 
II.  Polystominae 

Braun  (1893)  agreed  with  Saint-Remy  a3  to  the  classi- 
fication of  the  Onchocotyle.  the  general  classification  being  iden- 
tical with  that  of  van  Beneden,  i.e.,  the  sub-orders  Monogenea  and 
Djgenea  were  retained. 

Cerfontaine  in  1899  placed  in  the  Octocotylidae  those 
forms  having  eight  posterior  suckers.  The  organs  of  the  appendix 
having  been  shown  to  be  suckers,  he  accordingly  placed  the  Onchoco- 
tyle  _in  this  family,  and  created  three  genera:  the  Squalonchoco- 

tyle.  the  Acanthocotyle.  and  the  Ra.1  onchocotyle . 

Monticelli's  classification  was  adopted  by  Pratt  in  hi3 
key  to  the  trematode3  which  appeared  in  1900,  and  the  Onchocotyle 
were  again  placed  as  a genus  of  the  family  Polystomidae: 

Order  Sub-order  Family  Sub- family  Genus 

I. Trematoda  I .Hetercotylea  I . Polystomidae  I.Polystomae  I . Onchocotyle 

In  the  latest  work  dealing  with  the  classification  of 
trematodes,  that  of  Ward  in  1918,  the  original  grouping  of  van 
Beneden  into  Monogenea  and  Djgenea  is  used.  His  key  shows  the 
following  classification: 


• • 


-9- 


Class  - Trematoda. 

Sub- class  - Monogenea. 

Order  - Polyoplsthocotylea  (Odhner) 

Families: 

I.  Octocotylidae 

II.  Microcotylidae 

III.  Poly3tomidae 

He  draws  the  following  distinctions: 

"With  two  oral  suckers  and  with  genital  hooks. 

Family  Octocotylidae. 

Family  Microcotylidae. 

"Anterior  end  pointed,  without  suckers  or  special  organs, 
Family  Polystomidae. " 

This  very  clearly  places  the  Onchocotyle  in  the  Polystomidae  and 
not  in  the  Octocotylidae . Pratt  in  his  key  in  1900  also  placed 
the  Onchocotyle  under  the  Polystomidae  in  a similar  fashion. 

The  following,  then,  is  the  systematic  position  given 
to  the  Onchocotyle: 

Class  - Trematoda 

Sub-class  - Monogenea 

Order  - Polyopisthocotylea  Odhner. 

Family  - Polystomidae  van  Beneden. 

Genus  - Onchocotyle. 


. 


- 10- 

V.  Comparison  of  Onchocotyle  Wardi,  n.  sp.  with  the 
Other  Species  of  the  Genus 

In  considering  the  various  species  of  the  genus  On cho- 
co tyle  in  order  to  test  the  position  of  the  form  studied,  certain 
known  species  may  he  set  aside  at  the  beginning  as  obviously  so 
different  as  to  require  little  or  no  consideration.  Q.  batis, 

0.  prenanti,  and  Q.  alba,  in  which  the  digestive  tract  ramifies 
within  the  fixation  disk,  and  Q.  canicula,  and  Q.  appendiculata, 
in  which  genital  hooks  are  present,  are  evidently  very  different. 

Goto  emphasizes  the  importance  of  the  hooks  in  classi- 
fication and  thinks  that  they  alone  are  sufficient  for  identifica- 
tion. In  separating  and  distinguishing  the  species  of  Onchocotyle 
I have  relied  upon  the  hooks  to  a great  extent.  Measurements  were 
obtained  by  stepping  off  with  a pair  of  dividers  the  distance  along 
the  median  line  from  end  to  end  and  correcting  for  the  magnifica- 
tion. Cerfontaine ’ s figures  were  used  for  this  with  the  exception 
of  0.  wardi,  for  which  my  own  figure  (Fig.  9),  was  used.  The 
measurements  of  the  eggs  were  obtained  in  a similar  fashion,  and 
in  each  case  the  greatest  length  and  breadth  is  given.  I am 
unable  to  find  a record  of  the  size  of  the  egg  of  Q.  appendiculata. 
Van  Beneden  figures  one  but  does  not  state  the  magnification.  The 
egg  is  unknown  in  Q.  spinacis. 

The  preparation  of  the  hooks  for  examination  may  intro- 
duce an  error.  If  the  hooks  are  isolated  by  treating  the  fixation 


' 


( 


- ' * 


' 


11- 


disk  with  lactic  acid  for  a number  of  hours  and  then  dissecting, 
the  terminal  elevations  will  have  disappeared.  If,  however,  the 
fixation  disk  is  prepared  in  the  usual  way  for  to  to  mounts  in 
balsam  or  in  glycerine  gelatine  medium,  the  presence  or  absence 
of  terminal  elevations  may  be  determined. 

The  dimensions  of  the  hooks  and  eggs,  and  of  the  length 
of  the  body  of  the  various  species  are: 


Species 

Length  of 
Hooks 

Length 

Eggs 

of  Width  of 
Eggs 

Length 
Bo  dy 

of 

0.  vulgaris 

1428  p 

270  p 

110  F 

12 

mm. 

0.  can  is 

700  p 

155  p 

60  p 

7-8 

mm. 

0.  abbreviata 

900  p 

150  F 

60  p 

7-8 

ram. 

0.  spinacis 

942  p 

Egg  unknown 

8-9 

ram. 

0.  canicula 

528  p 

220  p 

130  P 

0.  appendiculata 

471  F 

No  data 

obtainable 

6-7 

mm. 

0.  borealis 

1685  p 

330  p 

120  P 

20 

mm. 

0.  griesa 

1514  p 

255  p 

67  p 

15 

ram. 

0.  alba 

1485  p 

225  p 

120  p 

8-9 

mm. 

0.  prenanti 

785  p 

260  p 

120  p 

8-9 

ram. 

0.  batis 

1800  p 

210  p 

105  u 

12  -15 

ram. 

0.  wardi 

1940  u 

296  p 

97  p 

17  -28 

mm. 

Q.  wardi  has  large  hooks  in  the  fixation  disk  which 
show  a variable  number  of  terminal  elevations.  Rarely  a hook 
shows  only  three  elevations,  usually  it  has  four  or  five.  This 
variation  may  be  found  among  the  hooks  of  the  same  disk,  where 


* 


* 


. 


-12- 

the  majority  show  four  or  five.  The  mature  egg,  as  found  in  the 
uterus  on  its  way  to  the  genital  atrium  never  shows  more  than  one 
polar  filament.  This  filament  is  never  greater  than  the  length 
of  the  body-proper,  and  usually  is  less,  averaging  in  length  about 
half  of  that  of  the  body-proper.  At  the  other  pole  is  a knob- 
like  body  which  varies  in  size  (Fig.  30). 

Of  the  species  not  already  eliminated  because  of  their 
more  obvious  differences,  the  following  have  specific  character- 
istics that  may  be  pointed  out.  0.  canis  has 'no  terminal  eleva- 
tions on  the  hooks;  0.  vulgaris  and  0.  abbreviata  have  two  terminal 
elevations  per  hook,  and  two  polar  filaments  on  each  egg;  0.  spin- 
acis  and  0.  griesa  have  three  terminal  elevations  per  hook,  and 
the  egg  of  the  latter  has  two  polar  filaments  (the  egg  of  0.  spin- 
acis  is  unknown).  0.  borealis  has  four  terminal  elevations  per 
hook  and  an  egg  with  two  polar  filaments. 

An  inspection  of  the  table  shows  that  0.  wardi  stands 
apart  from  the  great  majority  of  the  Onchocotyle  because  of  its 
greater  size,  larger  hooks  and  eggs.  That  species  that  approaches 
it  most  nearly  is  0.  borealis,  which  is  of  approximately  the  same 
length,  has  a hook  nearly  as  large,  and  an  egg  of  greater  size. 

A comparison  between  the  two  is  necessary  to  bring  out  the  specific 
differences. 

0.  borealis  has  not  been  carefully  worked  out,  so  that 
comparisons  of  the  various  systems  is  very  difficult.  Van  Bene den' s 
original  description  is  the  best,  Cerfontaine  gives  nothing  besides 
a careful  description  and  illustration  of  the  hooks  and  egg.  The 


. 


, 


’ 


, 

' 


. 


* 


I 


, ■ « J ; - . 


-13- 


general  size  of  the  body  in  the  two  species  is  the  same.  In  0. 
borealis  the  anterior  sucker  is  a wide,  shallow  and  thin  walled 
cup  with  a relatively  large  mouth  in  the  centre.  In  0.  wardi 
the  anterior  sucker  is  smaller  in  proportion  to  the  size  of  the 
body,  is  thick  walled  and  deep,  and  has  a small  mouth  in  the  cen- 
tre. Van  Beneden  does  not  mention  a genital  atrium  and  his  fig- 
ures do  not  indicate  that  he  found  one.  In  Q.  wardi  there  is  a 
genital  atrium  (Fig.  5). 

In  the  fixation  disk  certain  differences  are  evident. 

In  Q»  borealis  the  suckers  of  the  fixation  disk  are  very  distinct, 
with  the  lower  sides  of  each  tapering  slightly  inward  toward  the 
base.  In  Q.  wardi  this  is  not  the  case  (Fig.  7),  instead  the 
sides  of  the  suckers  continue  into  the  disk  proper  so  as  to  show 
no  distinct  line  of  demarcation  between  the  disk  and  the  suckers. 
The  difference  in  the  suckers  in  each  species  is  more  striking. 

In  0«  borealis  each  sucker  has  a mouth  that  is  distinctly  divided 
into  four  large  lobes  or  lips.  In  Q.  wardi  the  suckers  are  smaller 
and  have  smooth  mouths  without  a trace  of  lobes. 

As  indicated  in  the  table,  the  hooks  of  0.  wardi  are 
larger  than  those  of  Q.  borealis,  while  the  eggs  are  considerably 
smaller.  There  is  a further  difference  in  that  0.  borealis  has 
two  polar  filaments  per  egg,  while  0.  wardi  has  only  one.  The 
variations  in  the  number  of  terminal  elevations  has  already  been 
indicated. 

Van  Beneden  did  not  have  a clear  conception  of  the  rela- 


tions the  parts  of  the  reproductive  system  have  to  each  other  in 


, 


t 

’ iv 


, 


.1 


. 


• < 


-14- 


this  genus,  and  his  figures  show  he  misinterpreted  various  ducts. 

The  genital-intestinal  canal  and  the  posterior  end  of  the  uterus 
are  not  only  figured  as  vitellarian  ducts,  "but  are  made  to  lead 
to  the  vitellaria.  The  ootype  is  figured  as  a " vi tello sac . " With 
these  obvious  errors  corrected,  one  important  difference  may  be 
pointed  out.  In  0.  borealis  the  lateral  yolk-ducts  unite  and  the 
common  yolk-duct  empties  directly  into  the  ootype  at  its  anterior 
end.  At  the  other  end  of  the  ootype,  the  genital-intestinal  canal, 
the  oviduct  and  the  uterus  arise.  In  0.  wardi  this  is  not  the  case. 
In  0.  wardi  the  common  yolk- duct  formed  from  the  union  of  the 
lateral  yolk-ducts,  together  with  the  genito-intes tinal  canal  and 
the  oviduct,  all  unite  and  a short  duct  leads  to  the  ootype,  join- 
ing it  at  its  posterior  end.  The  uterus  arises  from  the  anterior 
end.  These  differences  are  shown  in  the  text  figures  1 and  2. 

The  differences  between  Q.  borealis  and  0.  wardi  may 
be  summed  up  briefly  as: 

1.  A difference  in  the  anterior  suckers. 

2.  A genital  atrium  is  present  in  0.  wardi  and  not  indi- 
cated in  0.  borealis. 

3.  The  eggs  of  Q.  borealis  are  larger  and  have  two  polar 
filaments,  while  the  eggs  of  0.  wardi  have  one  polar  filament  each. 

4.  The  hooks  of  0.  wardi  are  larger  than  those  of  0. 

borealis. 

5.  Each  sucker  of  the  appendix  of  0.  bo real is  has  a 
mouth  with  four  lobes,  while  in  0.  wardi  the  mouth  is  not  lobed. 

6.  There  is  a difference  in  the  connection  of  the  uterus, 


yolk-duct,  oviduct  and  genital-intestinal  canal  with  the  ootype. 


« 


, 


, 

. 


, 


, 


. 

, . 


. 


Text  figures  . 


Figure  1.  Onclioc style  wardi  X20 

Figure  2 Onchocotyle  borealis 

g*i  genitoint estinal  canal 

oot.  ootjrpe 
ov.  ovary 
ovid  . oviduct 
r.s.  r ecapaculurri  seminal  e 
ut.  uterus 


-15- 


VI. 

Key  to  the  Species  of  the  Genu3  Onchocotyle 

1 (17) 

Digestive  tract  does  not  ramify  within  the  fixa- 
tion disk 2 

2 (5) 

Genital  hooks  present  3 

3 (4) 

Large. hooks  of  fixation  disk  with  four  terminal 
elevations,  free  end  of  hook  tapers  slightly. 
Genital  hooks  roughly  T-shaped.  Egg  220  ji  in 
length,  130  jd  in  width,  one  polar  filament.  Large 
hooks  528  jd  in  length. 

0.  canicula  ( Cerfontaine , 1899). 

4 (3) 

Large  hooks  of  fixation  disk  with  more  than  four 
terminal  elevations,  free  end  of  hook  slightly 
swollen.  Genital  hooks  roughly  L- shaped.  Egg 
with  two  polar  filaments.  Large  hooks  471  ja  in 
length;  body  length,  6 - 7 ram. 

0.  appendiculata  (Kuhn,  1830)  Diesing  1850. 

5 (2) 

Genital  hooks  absent  6 

6 (7) 

Large  hooks  of  fixation  disk  without  terminal 
elevations,  egg  155  ;u  in  length,  60  ^u  in  width, 
with  two  long  polar  filaments.  Large  hooks 
700  jd  in  length;  body  length,  7-8  mm. 

0.  canis  (Cerfontaine,  1899)  Pratt  1900 

7 (6) 

Large  hooks  of  fixation  disk  with  terminal  ele- 

vations 


8 


-16- 


8 ( 11,14)  Each  hook  with  two  terminal  elevations  

9 (10)  Egg  with  short  equal  polar  filaments. 

Egg  270  ju  in  length,  110  ji  in  width.  Large 
hooks  1428  ji  in  length;  tody  length,  12  mm. 

0.  vulgaris  ( Cerfontaine , 1899) 

10  (9)  Egg  with  very  long  polar  filaments.  Egg 

150  ju  in  length,  60  ja  in  width.  Large  hooks 
900  jj.  in  length;  body  length  7-8  mm. 

0.  abbreviata  Ols son  1876 

11  (8,14)  Each  hook  with  three  terminal  elevations  .... 

12  ( 13)  Hooks  on  appendix  Y-shaped,  with  the  three 

prongs  approximately  equal,  the  two  prongs 
embedded  in  mesenchyma  diverging  widely.  Egg 
unknown.  Large  hooks  942  ji  in  length;  body 
length,  8-9  mm.  0.  sninacis  Goto  1894 

13  (12)  Hooks  on  appendix  not  Y-shaped,  two  embedded 

prongs  very  short.  Egg  255  /a  in  length,  67  yM 
in  width;  with  two  short  equal  polar  filaments. 
Large  hooks  1514  ju  in  length;  body  length  15  mm. 

0.  griesa  (Cerfontaine,  1899) 

14  (8,11)  Each  hook  with  four  or  more  terminal  elevations  . 

15  (16)  Suckers  on  appendix  each  with  a mouth  divided 

into  four  lobe3.  Terminal  elevations  four.  Egg 
330  ja  in  length,  120  ji  in  width;  with  two  equal 
polar  filaments.  Large  hook  1685  yu  in  length; 
body  length,  20  mm.  0.  borealis  van  Beneden  1853 


12 


15 


. 

, 

, • 

4 ' 

. 

, 

. 

. 


, 


-17- 


16  ( 15) 


17  (1) 


18  (21) 

19  (20) 

20  ( 19) 

21  ( 18) 


Suckers  on  appendix  with  smooth  circular  mouths; 
terminal  elevations  variable,  four  to  five.  Egg 
29  6 ji  in  length,  97  ja  in  width;  with  one  polar 
filament.  Large  hooks  1940  ji  in  length;  body 
length  17  - 28  mm.  Q.  wardi . n.  sp. 

Digestive  tract  ramifies  within  fixation  disk. 
Eggs  without  polar  filaments,  but  with  spher- 


oidal polar  bodies 18 

Large  hooks  of  fixation  disk  with  five  ter- 
minal elevations 19 


Terminal  elevations  all  pointed.  Egg  210  yu 
in  length,  105  ji  in  width.  Large  hooks  1800  ^u 
in  length;  body  length,  12  - 15  mm. 

Q.  batis  ( Cerfontaine , 1899) 
Terminal  elevations  not  all  pointed,  the  one 
next  the  claw  being  largest  and  very  blunt.  Egg 
260  yU  in  length,  120  yu  in  width.  Large  hooks 
785  p.  in  length;  body  length  8-9  mm. 

0.  prenanti  St.  He my  1890 
Large  hooks  of  fixation  disk  with  six  terminal 
elevations,  the  one  farthest  from  the  claw  much 
larger  than  the  remainder.  Egg  225  u in  length, 
120  fx  in  width.  Large  hooks  1485  u in  length; 
body  length,  8-9  mm. 

0.  alba  (Cerfontaine.  1899). 


-18- 

VII.  The  Morphology  of  Onchocotyle  Wardi,  N.  Sp. 

1.  The  General  Form  and  Size 

The  external  shape  of  the  various  numbers  of  the  genus 
On choco tyle  has  been  rather  aptly  compared  by  various  authors  to 
a hammer.  The  body  proper  corresponds  to  the  handle,  the  fixation 
disk  and  appendix  represent  the  iron  head  and  claw,  the  latter 
being  well  illustrated  by  the  long  appendix  which  is  bifurcated 
at  the  free  end. 

The  worms  vary  somewhat  in  size,  specimens  studied  rang- 
ing from  17  to  28  ran.  in  length  from  the  anterior  tip  to  the  con- 
striction of  the  body  to  which  the  fixation  disk  is  attached;  from 
1.5  to  3 mm.  in  width;  and  unifonnly  1 mm.  in  thickness;  the  lat- 
eral direction  being  considered  as  width,  and  the  dorso-ven tral 
direction  as  thickness.  The  disk  is  oval  in  shape,  affixed  at 
right  angles  to  the  body  proper.  The  disks  are  rather  uniform  in 
size,  body  variation  being  chiefly  in  the  length  of  the  body-proper. 
The  disks  are  about  2 mm.  wide,  and  3 mm.  long;  the  width  being 
measured  in  the  same  plane  as  that  of  the  body-proper,  and  the 
length  in  a plane  at  right  angles  to  the  width,  or  in  a dorso- 
ventral  relation  to  the  body  proper.  The  appendix  varies  in  size 
from  3 to  4 rnm.  in  length,  1 mm.  in  width,  and  0.5  mm.  in  thick- 
ness. While  these  dimensions  are  average  dimensions,  there  is 
very  little  variation  from  these,  the  greatest  variation  being,  as 
noted  above,  in  the  length  of  the  body  proper. 


, 


1 

, 

, 


-19- 

Three  distinct  regions  of  the  body  are  quite  clearly 
differentiated,  the  body  proper,  the  fixation  disk,  and  the  appen- 
dix. The  body  proper  is  rather  uniform  in  width  and  thickness, 
tapering  gradually  at  the  anterior  end,  and  more  sharply  at  the 
posterior  end  where  it  is  joined  to  the  fixation  disk  by  a narrow 
neck.  The  body  is  roughly  ovoid  in  cross-section,  being  flat  or 
slightly  concave  on  the  ventral  side  and  always  more  or  less 
convex  on  the  dorsal  side.  The  anterior  sucker  is  situated  at  the 
anterior  end  of  the  body,  slightly  ventral  in  position.  The 
mouth  is  within  the  sucker,  at  the  bottom  of  the  conical  pit.  The 
sucker  is  without  hooks. 

The  genital  atrium  is  situated  on  the  ventral  surface 
of  the  body.  This  is  a shallow  depression  into  which  the  oviduct 
opens,  and  into  which  the  cirrus  projects.  Goto  found  no  genital 
atrium  in  Qnchocotyle  spinacis,  but  in  this  species  it  is  very 
clearly  present.  The  cirrus  and  oviduct  form  a tiny  mound  in  the 
centre  of  the  genital  a.trium  which  is  visible  to  the  naked  eye. 
There  are  no  genital  hooks.  Just  posterior  to  the  genital  atrium, 
on  the  ventral  surface,  and  considerably  off  of  the  median  line, 
are  the  two  external  orifices  of  the  vaginae. 

Anterior  to  the  genital  atrium,  and  on  the  dorsal  surface 
are  the  external  orifices  of  the  parallel  excretory  canals  that 
run  thru  almost  the  entire  body.  The  openings  are  very  minute  and 
practically  invisible  in  the  toto  preparations.  In  cross-sections, 
however,  they  are  readily  demonstrated. 

The  fixation  disk  at  the  posterior  end  of  the  body  is 


, 


or  7 it«  • jo 


. 

* 


, 

. 


I 


■ 


. 

♦ 


-20- 


at  once  a most  interesting  and  curious  structure.  On  an  oval 
disk  are  arranged  in  two  arcs  three  pairs  of  suckers,  the  arcs 
extending  in  a dorso- ventral  direction  with  the  convexity  of  each 
arc  toward  the  centre  of  the  disk.  Each  of  the  six  suckers  con- 
tains a crescent-shaped  hook,  with  a minute  and  very  sharp  claw 
on  the  free  end.  These  hooks  are  embedded  on  the  ventral  side  of 
the  suckers.  The  result  is  that  all  the  fixation  points  of  the 
hooks  extend  tov/ard  the  dorsal  surface.  The  suckers  are  as  large 
as  the  hookless  anterior  sucker,  and  the  musculature  indicates 
a surprising  adhesive  power. 

Prom  a mechanical  viewpoint  the  fixation  disk  would  be 
weakened  by  the  hooks  of  the  disks  all  lying  in  the  same  general 
direction.  A disturbing  force  applied  from  the  dorsal  surface 
would  tend  to  disengage  the  hooks  and  cause  the  hold  to  be  lost. 
But  to  resist  and  overcome  this  mechanical  weakness  a most  strik- 
ing modification  has  developed  - the  appendix.  The  appendix  is 
situated  on  the  median  line  between  the  two  row's  of  suckers,  and 
on  the  dorsal  side,  exactly  at  the  point  of  weakness.  It  is  bi- 
furcated at  its  free  end,  and  each  bifurcation  has  a small  ellip- 
soidal sucker,  without  hooks.  This  pair  of  suckers,  altho  much 
smaller  than  the  other  three  pairs,  is  ample  to  check  any  ten- 
dency to  slip. 

Unlike  the  Polystoma,  the  fixation  disk  does  not  bear 
hooks  other  than  those  in  the  suckers  and  on  the  appendix. 

The  hooks  found  in  the  three  pairs  of  large  suckers  are 
crescent-shaped  bodies,  tapering  slightly  toward  the  buried  end. 


, 

> 


■ 


• ■ 


1 


, 


t 

. 

! 

, 


. 


-21- 


The  free  end  of  each  hook  has  a tiny  extremely  sharp  claw  which 
curves  inward  toward  the  mouth  of  the  sucker.  The  hooks  are  quite 
smooth,  but  somewhat  irregular  at  the  inner  end,  which  is  buried 
in  the  muscular  wall  of  the  sucker. 

The  hooks  of  the  appendix  are  very  tiny  and  readily 
overlooked.  Each  is  a triradiate  body,  with  the  two  shorter  prongs 
embedded  in  the  mesenchyma,  and  with  the  longer  and  extremely 
sharp  prong  free. 


2.  The  Digestive  System 

The  digestive  system  is  by  far  the  most  prominent  sys- 
tem in  the  body  of  this  trematode.  Due  to  the  dark  colored  gran- 
ular matter  contained  therein,  the  general  form  of  the  intestine 
may  be  seen  in  the  preserved  specimens  without  clearing,  and  when 
cleared,  either  with  or  without  staining,  the  entire  system  shows 
up  beautifully  clear  and  distinct  to  very  fine  details. 

The  mouth,  as  previously  stated,  is  contained  within  the 
anterior  sucker,  is  funnel-shaped,  and  communicates  with  the  phar- 
ynx by  means  of  a very  short  tube  (Fig.  26).  The  pharynx  is  an 
ellipsoidal  body,  and  the  passage  thru  it  varies  in  form  from 
elliptic  to  a rather  irregularly  shaped  tube  (Fig.  32).  The  var- 
iation is  due  very  probably  to  the  state  of  contraction  at  the 
time  of  death,  and  the  circular  form  is  the  natural  form.  The 
oesophagus  is  rather  long  and  communicates  with  the  two  digestive 
crura.  There  is  a ventral  diverticulum  which  underlies  the  phar- 


-22- 


ynx  and  extends  anteriorly  for  a considerable  distance,  so  that  a 
cross-section  of  the  pharynx  quite  often  shows  a portion  of  the 
oesophagus.  There  are  no  salivary  glands. 

The  two  crura  extend  thruout  the  length  of  the  body 
proper,  lying  laterally  near  the  outer  edges.  In  the  region  of 
the  constriction  joining  the  body  proper  and  the  fixation  disk, 
the  crura,  reunite  and  the  single  tract  continues  into  the  fixa- 
tion disk,  (Fig.  25).  Within  the  disk  the  tract  divides  again 
into  a shorter  and  a longer  lobe.  The  shorter  lobe  ends  blindly 
within  the  disk,  but  the  longer  lobe  extends  into  the  appendix 
almost  to  its  extremity.  There  it,  too,  ends  blindly.  The  crura 
for  a short  distance  posteriorly  from  the  oesophagus  are  simple 
tubes,  following  the  conformation  of  the  body,  which  in  this  region 
is  expanding  to  the  uniform  width  which  characterizes  the  body 
thruout  its  greater  extent.  They  soon  begin  to  branch  out,  how- 
ever, and  for  the  major  portion  of  their  lengths  the  crura  are 
divided  on  the  outer  sides  into  a complicated  system  of  lobes 
(Fig.  27).  These  lobes  extend  laterally,  dorsally,  and  ventrally. 
At  the  posterior  end  of  the  body,  where  the  crura  unite  into  a 
single  common  duct,  the  lobes  disappear,  and  the  digestive  tract 
within  the  fixation  disk  is  not  lobed. 

The  digestive  tract  is  lined  by  irregularly  shaped  cells 
upon  a tunica  propia.  The  cells  are  very  amoeboid  in  shape,  but 
are  generally  club-shaped,  connected  with  the  wall  of  the  intes- 
tine by  narrow  stalks  (Figs.  29,  30).  The  nuclei  are  found  in  the 
bases  of  the  stalks.  The  structure  of  these  cells  is  quite 


, 

. 


« 


, 


. 

. 


« 


. 


-23- 


gen  er  ally  obscured  by  the  great  number  of  granular  bodies  within 
and  clustered  on  the  surfaces  of  the  cells.  These  bodies  range 
in  color  from  a greenish  brown  to  quite  black  and  are  innumerable. 
The  majority  seem  to  be  on  the  surface  of  the  cells. 

The  nature  of  these  dark  granular  bodies  is  still  in 
doubt.  Three  theories  have  been  advanced  by  various  investigators. 
First,  that  they  are  food  particles.  Second,  that  they  are  zymo- 
genic and  serve  as  agencies  in  facilitating  digestion.  The  third 
suggestion  is  that  they  are  the  indigestible  portion  of  the  food 
materials.  The  possibility  of  the  granules  being  food  material 
seems  very  unlikely  because  of  their  uniform  size,  shape  and  ap- 
pearance. Food  materials  would  show  most  certainly  tra.ces  of 
digestion,  and  one  would  expect  a considerable  variation  in  size 
and  structure.  The  second  theory,  that  the  bodies  are  zymogenic, 
is  more  plausible,  but  it  appears  that  were  it  correct,  more  of 
these  granules  would  be  found  distributed  in  the  lumen,  and  fewer 
clustered  on  the  surface  end  within  the  cells.  That  is,  if  scat- 
tered thruout  the  food  particles  the  action  would  be  facilitated, 
whereas  the  action  must  necessarily  be  localized  when  they  are 
grouped  in  clusters.  The  third  explanation,  that  they  are  the 
indigestible  portion  of  the  food  is  also  very  plausible,  but 
again  one  would  not  expect  to  find  such  a uniform  size,  color, 
and  structure. 

When  the  various  positions  of  these  granules  are  con- 
sidered, within  the  cells,  clustered  on  the  surfaces  of  the  cells, 
and  in  clusters  thruout  the  lumen,  the  possibility  of  their  being 


, 

t 

r 

’ 


' . ! 


1 


. 


-24- 

excretory  products  is  rendered  very  probable.  I think  it  probable 
that  the  club-shaped  portions  of  the  cells  are  gradually  filled 
with  these  excretory  bodies  and  that  they  then  become  detached 
from  the  narrow  stalks  and  are  expelled  from  the  lumen  by  way  of 
the  mouth.  Such  bodies  are  quite  numerous  in  the  lumen,  identical 
in  appearance  with  similar  bodies  attached  by  stalks  to  the  in- 
testinal wall.  Some  of  these  bodies  are  nucleated.  The  charac- 
teristic contractions  and  relaxations  of  the  whole  body  would  tend 
to  expel  the  fluids  of  the  lumen  and  with  them  the  excretory  bod- 
ies. 

3.  The  Excretory  System 

The  excretory  system  is  very  difficult  to  demonstrate, 
except  in  its  general  features.  In  toto  mounts  no  trace  of  an 
excretory  system  can  be  discovered,  and  in  the  cross-sections  only 
the  main  ducts  may  be  distinguished  with  certainty.  There  are  two 
main  ducts  on  each  side  of  the  body,  a greater  and  a lesser.  The 
larger  of  these  ducts  open  to  the  exterior  on  the  dorsal  side 
anterior  to  the  genital  atrium.  These  orifices  are  so  tiny  that 
they  cannot  be  seen  externally,  due  most  likely  to  the  contraction 
of  the  body  when  it  is  fixed.  They  can  be  demonstrated  readily, 
however,  in  sections  (Fig.  35).  The  ducts  have  walls  of  a struc- 
tureless tissue,  and  are  embedded  in  the  mesenchyma.  They  are 
ventral  to  the  digestive  crura  thruout  most  of  the  length  of  the 
body,  rising  gradually  in  the  vicinity  of  the  genital  atrium  to 
the  dorsal  surface  where  the  larger  open  to  the  exterior  (Fig.  35). 


, 


. 


< ■ 


. 


-25- 


There  is  a considerable  variation  in  the  diameter  of  these  ducts 
thruout  their  course,  but  in  the  oesophageal  region  the  two  com- 
municating with  the  exterior  are  considerably  expanded  into  what 
may  be  termed  bladders,  narrowing  down,  however,  before  reaching 
the  orifices.  Occasionally  traces  of  smaller  ducts,  and  doubtless 
tributary  to  the  main  ducts  may  be  seen  in  the  mesenchyma.  Eo th 
pairs  of  ducts  penetrate  a considerable  distance  into  the  fixation 
disk,  following  closely  the  digestive  tract.  No  traces  of  the 
flame  cells  were  found. 

4.  The  Reproductive  System 

Next  to  the  digestive  tract  in  prominence  is  the  repro- 
ductive system,  occupying  the  space  between  the  digestive  crura 
thruout  the  length  of  the  body,  and  staining  in  part  so  deeply  as 
to  be  very  conspicuous. 

The  male  reproductive  system  is  relatively  simple.  The 
many-lobed  testes  occupy  the  posterior  half  of  the  space  between 
the  crura,  and  show  little  regularity.  The  lobes  are  thin  walled, 
of  structureless  material,  and  vary  up  to  seven  in  number,  and 
considerably  in  size,  as  is  shown  by  cross-section.  The  cavities 
are  filled  with  the  sperm-cells  and.  the  accompanying  nurse  cells 
in  various  stages  of  development.  From  the  testes  extend  anter- 
iorly two  ducts,  the  vas  efferens,  which  unite  on  the  left  ventral 
side  of  the  bocty-  and  continue  forward  as  the  vas  deferens.  The 


vas  deferens  enlarges  considerably  in  the  anterior  half  of  the 


t 

, 


1 


. 

< 


‘ 


: " 

' •'  * ' • 1 • g • .j  -o  9C 


. 

. 

. 


■ ■ 


, • . ■ 


-26- 


bocLy,  and  is  coiled  and  doubled  back  on  itself  in  a peculiar 
fashion.  No  two  specimens  show  an  identical  in  this  coiling. 

This  enlarged,  coiled  portion  is  usually  filled  with  sperm  masses. 
It  communicates  with  the  cirrus  by  a large  straight  duct  which 
lies  just  beneath  the  uterus,  (Fig.  28).  The  cirrus  is  quite 
large  and  projects  into  the  uterus  and  the  genital  atrium  as  des- 
cribed later  on.  The  duct  of  the  cirrus  appears  to  be  ciliated, 
(Figs.  11,  12,  Plate  II),  the  vas  deferens  certainly  is  not. 

The  female  reproductive  system  occupies  the  anterior 
half  of  the  body  and  is  very  complex  (Fig.  28).  The  ovary  is 
found  on  the  right  side  of  the  body,  and  approximately  midway  be- 
tween the  extremes  of  the  body  proper.  It  is  an  irregularly 
shaped  body  which  doubles  upon  itself  and  communicates  with  the 
ootype  by  means  of  a short  oviduct.  The  ovary  when  sectioned  is 
seen  to  consist  of  germinal  cells  in  various  stages  of  maturity. 
The  earliest  stage  (Fig.  16)  is  that  of  a compact  mass  of  cells, 
with  or  without  nuclei,  and  of  irregular  shapes.  Farther  down 
the  ovary,  i.e.,  nearer  the  oviduct,  other  stages  (Figs.  17,  18, 

19)  may  be  discerned,  in  which  the  mature  egg- cells  are  embedded 
in  a structureless  matrix  which  breaks  up  and  liberates  the  ma- 
tured cells.  The  ovary  communicates  v/ith  the  ootype  by  means  of 
a short  oviduct.  Cross-sections  of  the  oviduct  appear  to  be 
ciliated,  but  closer  examination  shows  that  the  lining  is  of  amoe- 
boidal  cells,  having  large  distinct  nuclei,  each  with  a definite 
nucleolus. 


• . 1 I < - • 

' 


t 

; 


• . ... 


. ' 


-27- 

The  receptaculum  seminale  is  a large  thin-walled,  oval 
sac  connected  to  the  oviduct  Toy  a short  tube  which  has  two  dis- 
tinct enlargements,  which  in  cross-section  show  cross-filaments, 
that  appear  to  be  muscular  fibers,  but  I have  not  been  able  to 
demonstrate  them  as  such.  If  they  are  muscles,  they  would  serve 
as  valves,  opening  and  closing  the  duct  which  communicates  with 
the  oviduct  and  thereby  controlling  fertilization.  The  receptacu- 
lum seminale  lies  opposite  the  ovary  on  the  left  side  of  the  body. 
In  all  specimens  examined  the  receptaculum  seminale  was  almost 
completely  filled  with  sperm  masses  which  stain  intensely. 

Communicating  with  the  ootype  are  also  the  geni to-intes- 
tinal  canal,  and  the  yolk  duct  which  is  also  the  medium  of  commu- 
nication with  the  vaginae.  The  geni to-intes tinal  canal  is  a short 
duct  with  rather  thin  walls  that  leads  directly  into  the  right 
digestive  crus.  In  cross-section  both  nuclei  and  nucleoli  can  be 
made  out  readily,  altho  Go  to  describes  it  as  wholly  destitute  of 
nuclei.  He  mentions  a lining  with  fine  cillia  which  I have  not 
been  able  to  demonstrate.  The  opening  into  the  intestine  is  very 
minute  (Figs.  20,  21,  22,  23),  and  shows  no  evidence  of  a valve. 
The  ootype  is  a spindle-shaped  body,  surrounded  by  shell  glands 
(Fig.  33).  In  cross-section  it  presents  a stellate  appearance 
due  to  the  thickenings  of  the  lining  membrane.  In  each  of  the 
thickenings  is  a nucleus  with  a distinct  nucleolus.  The  wall  of 
the  ootype  is  a thin  darkly  staining  structure  without  nuclei 
(Fig.  15). 

The  uterus  is  a small  straight  duct  leading  from  the 


■ 

' 


, . 


. 


, 

1 



• . 


-28- 


ootype  to  the  genital  atrium.  It  is  a relatively  thick-walled 
duct,  showing  nuclei  and  nucleoli,  hut  as  is  true  of  all  tissues 
in  the  parasite,  no  cell  outlines  (Fig.  10).  It  is  ciliated 
thruout  its  course.  Shortly  before  the  genital  atrium,  the  uterus 
enlarges  dorsally.  It  is  at  this  place  the  cirrus  enters  the 
uterus.  In  cross-sections  this  may  he  seen  very  clearly,  the 
uterus  being  a large,  thin-walled  tube  with  the  thick-walled 
cirrus  occupying  the  ventral  side  (Fig.  ll) . Farther  on  the  cirrus 
is  seen  lying  wholly  within  the  uterus  (Fig.  12).  This  enlarge- 
ment leads  into  the  genital  atrium,  into  which  the  cirrus  projects 
as  a small  conical  body  (Figs.  4 and  5). 

The  vitellaria  are  two  multilobed  bodies  extending  thru- 
out the  major  portion  of  the  body.  By  means  of  cross-sections  the 
vitellaria  are  seen  to  extend  from  the  anterior  tapering  portion 
of  the  body  back  posteriorly  to  almost  the  region  in  which  the 
digestive  crura  reunite.  The  vitellaria  surround  the  crura.,  but 
the  lobes  are  more  numerous  on  the  dorsal  side.  The  lobes  are 
filled  with  the  yolk-granules,  tiny  spherical  bodies  of  a greenish 
yellow  color.  The  lobes  have  very  thin  walls,  which  are  often 
very  difficult  to  demonstrate.  The  two  yolk  ducts  leading  from 
the  lateral  vitellaria  unite  in  the  median  line,  and  a single  yolk 
duct  leads  to  the  ootype.  The  paired  yolk  ducts  are  usually  en- 
larged into  yolk  reservoirs  which  store  the  yolk  material  until 
needed. 

The  vaginae  are  paired  ducts  which  have  their  external 
orifices  on  the  ventral  surface  just  anterior  to  the  genital  atrium 


... 


- 

1 

. 

. . 

. 

" I 


* 


-29- 


and  situated  laterally  to  it.  The  orifices  are  very  minute  and 
are  made  out  with  difficulty  in  the  unstained  and  uncleared  whole 
worms.  They  are,  however,  readily  found  in  the  cross-sections 
(Fig.  14).  From  these  orifices  two  small  ducts  lead  posteriorly, 
enlarging  immediately  to  considerable  size,  and  then  tapering  as 
they  extend  posteriorly.  Quite  often  one  or  two  constrictions 
will  be  present  in  the  vaginae.  The  vaginae  are  ciliated  (Fig.  13) 
and  lead  into  the  paired  yolk  ducts  of  the  vitellaria,  which  com- 
municate by  means  of  the  single  yolk  duct  with  the  ootype  and 
recept&culum  seminale. 

The  mature  eggs  are  found  in  the  uterus  and  are  never 
numerous.  From  one  to  two  are  found  in  a single  specimen.  The 
eggs  are  probably  passed  out  as  soon  as  fully  mature.  The  eggs 
are  ovoid,  tapering  at  each  end,  with  polar  filaments  which  vary 
considerably  in  length  on  the  same  and  different  individuals.  The 
eggs  average  about  296/ microns  in  length,  exclusive  of  the  var- 
iable polar  filaments. 

The  process  of  reproduction  is  probably  as  follows: 

The  sperms  are  formed  in  great  numbers  and  are  stored  in  the 
multi-lobed  seminal  vesicle.  In  coitus  the  sperm  masses  a,re  in- 
troduced into  the  vaginae  by  means  of  the  cirrus.  Aided  by  the 
ciliated  inner  surfaces  of  the  vaginae,  the  sperm  masses  pass 
posteriorly  into  the  lateral  yolk  ducts,  and  from  them  into  the 
common  median  yolk  duct.  This  communicates  with  the  vesicle 
formed  by  the  common  junction  of  the  yolk  duct,  oviduct,  ootype, 
and  genito-intestinal  canal.  From  this  vesicle  the  spern  masses 


t 


. 


■ „ 
t 


. 


, 

' 


-30- 


pass  into  the  oviduct  and  are  stored  in  the  recep taculum  seminale. 
The  egg- cells  as  they  are  formed  in  the  ovary  pass  down  the  ovi- 
duct, are  fertilized  in  the  oviduct,  and  then  pass  into  the  ootype. 
There  the  yolk  material  is  added,  and  the  enclosing  shell  added. 

The  completed  egg  passes  into  the  uterus,  and  by  the  ciliary  ac- 
tion is  carried  anteriorly  to  the  genital  atrium  where  it  is 
liberated. 

The  part  played  by  the  geni to-intes tinal  canal  is  as 
yet  in  doubt.  There  is  no  agreement  among  investigators  as  to 
its  function.  The  suggestion  that  it  is  a passage  way  thru  which 
surplus  yolk  material  is  excreted  has  been  offered,  but  not  proven, 
and  does  not  appear  very  plausible. 

5.  The  Nervous  System 

Scarcely  anything  of  the  nervous  system  can  be  demon- 
strated. Above  the  oesophagus  are  two  conspicuous  ganglia,  from 
which  nerves  may  be  traced  a short  distance  anteriorly  and  very 
little  farther  posterior.  The  two  lateral  nerve  trunks  may  be 
traced  for  a greater  distance.  Apparently  there  is  little  or 
no  difference  between  the  nervous  system  of  this  species  and  0. 


borealis  as  far  as  can  be  determined. 


, 


, 

■ 


• • ' 


. 


-31- 


VIII.  Conclusions 


1.  The  genus  Onchocotyle  belongs  to  the  family 
Po lystomidae  van  Bene den,  of  the  order  Po lyopi s thoco tylea 
Odhner. 

2.  A new  species,  0.  wardi,  is  described,  resem- 
bling most  nearly  0.  borealis. 


. 


-32- 


van  Bene&en 
1653 


van  Beneden 
1853 


van  Beneden 
1861 

Braun,  M. 
1893 

Cerfontaine 

1899 

Diesing,  K. 
1858 


IX.  Bibliography 


P.  J. 

Sur  un  poisson  rare  de  nos  cotes  (Sumnus  glacialis) 
et  es  parasites. 

Bull.  Acad.  roy.  d.  sc.  de  Belg.,  20:  2 (6):  258-263. 
P.  J. 

Espece  nouvelle  du  genre  Onchocotyle,  vivant  sur 
les  branchies  Sumnus  glacialis. 

Bull.  Acad.  roy.  d.  sci.  de  Belg.,  20:  3 (9):  69-72. 
P.  J. 

Memoire  sur  les  vers  intestinaux. 

Compt . rend.  Acad.  sci.  (Supplement).  2:  54-59. 

Bronn,  Klaesen  und  Ordnugen  des  Thier-Reiches . 
Vermes.,  4:  538-539. 

P. 

Contribution  a 1* etude  des  Octocotylides . 

Arch.  Biol.,  16:  345-478. 

M. 

Revision  der  Myzelminthes.  Abth.  Trematoden. 
Sitzungsberichte  der  mathem. 

Naturw.  Classe  der  Kaiserl. 

Academie  der  Wissenschaften.  32:  307-339. 


-33- 


Goode,  G.  B. 
1884 


Goto,  S. 
1894 


Monticelli , 
1903 

Odhner,  J . 
1905 

Pratt,  H.  S. 
1900 


Pratt,  K.  S. 
1916 

Saint-Remy , 
1892 


The  Fisheries  and  Fishery  Industries  of  the 
United  States. 

Sec.  I.  Nat.  Hist,  of  Useful  Aquatic  Animals. 
P.  675. 

Studies  on  the  Ectoparasitic  Trematodes  of  Japan. 
Jr.  Coll.  Sci.  Imperial  Univer.  Tokyo,  Japan, 

8:  1-273. 

. S. 

Per  una  nova  clas3if icazione  digli  "Hetercotylea. " 
Monitore  zool.  ital.  Firenze.,  14:  12:  334-336. 

Die  Trematoden  de  arktischen  gebietes. 

Fauna  artica.,  4:  291-372. 

Synopses  of  N.  A.  Invertebrates. 

XII.  The  Trematodes,  Pt.  I.  The  Hetercotylea, 
or  Monogenetic  Forms. 

Amer.  Nat.  34:  645-662. 

A Manual  of  the  Common  Invertebrate  Animals. 
Chicago,  p.  171-179. 

• 

Synopsis  Des  Trematodes  monogenesis. 

Revue  Biol,  du  Nord  de  la  France,  4:  1-92. 


-34- 


Saint -Re  my,  G. 

1898  Complement  &u  Synopsis  Der  Trematodes  monogenesis. 

Archiv.  Parasit.,  1:  4:  558. 

Scott,  J. 

1901  Notes  on  Some  Parasites  of  Fishes. 

Ann.  Rep.  Fishery  Board  Scotland.  Glasgow,  p.  151. 
Stiles,  C.  W.,  and  Hassell,  A. 

1908  Trematoda  and  Trematoda  Diseases. 

Hygienic  Lab.  Bull.  No.  37.  Washington. 


Ward,  H.  B, 
1910 


Ward,  H.  B. 
1918 


Some  Parasites  of  the  Sleeper  Shark  in  Icy  Straits, 
Alaska. 

Science,  N.  S.  31:  804:  836-837. 

Ward,  H.  B.  and  Whipple,  G.  H.  Fresh  Water 
Biology.  Parasitic  Flatworms,  365-453. 

New  York. 


■ 


. 


-35- 


X.  Explanation  of  Plates 


All  drawings  were  made  with  the  camera  lucida,  and 
then  reduced  approximately  one-half. 


Plate  I 


Figure  1. 
Figure  2. 
Figure  3. 
Figure  4. 
Figure  5. 

Figure  6. 
Figure  7. 
Figure  8. 

Figure  9. 


Ventral  view  of  complete  specimen,  x 6 
Left  lateral  view  of  complete  specimen,  x 6 
Anterior  sucker,  x 9 
Cirrus,  x 9 

Anterior  portion  of  the  body  (ventral), 
showing  sucker,  genital  atrium,  and 
orifices  of  vaginae.  x 9 
Fixation  disk  and  appendix,  x 9 
Fixation  disk  and  appendix,  x 9 
Section  thru  posterior  sucker,  x 52 
h.  section  of  hook 
Two  hooks  from  posterior  suckers, 
isolated  with  lactic  acid. 


Plate  II. 

Figure  10.  Uterus  in  cross-section,  x 609 

Figure  11.  Uterus,  with  cirrus  entering  it.  x 304 

Figure  12.  Uterus,  with  cirrus  completely  within  it.  x 304 

Figure  13.  Vagina  in  cross-section,  x 477 

Figure  14.  Opening  of  vagina  to  exterior,  x 304 

Figure  15.  Oo type  in  cross-section  x 207 


. 


. 


. 


. 


-36- 


Figures  16, 
Figures  20, 

Figure  24. 

Plate  III. 

Figure  25. 
Figure  26. 

Figure  27. 
Fi  gure  28 . 


Figure  29. 
Figure  30. 
Figure  31. 


17,  18,  19.  Sections  through  the  ovary, 
showing  stages  in  maturing  of  the  eggs,  x 477 
21,  22,  23.  Serial  sections  through  genito- 
intestinal  canal  at  the  point  of  emptying 
into  the  right  digestive  crus,  x 304 
Oviduct  in  cross-section,  x 609 


The  digestive  crura.  x 6 
Anterior  sucker,  mouth,  pharynx, 
oesophagus  and  anterior  ganglia,  x 118 
Longitudinal  section  thru  digestive  crus,  x 37 
Schematic  view  of  reproductive  systems. 


d.  cr . 

right  digestive  crus 

g.  i . 

geni to- intes tinal  canal 

oot . 

oo type 

ov. 

ovi due  t 

r.  s . 

recep taculum  semina le 

tes . 

testes 

u t. 

uterus 

vag. 

vagina 

v.  d. 

vas  deferens 

vit. 

vitellaria 

Lining  of  digestive  crus.  x 612 
Mature  eggs  from  uterus,  x 47 
Cells  of  digestive  crus,  x 612 


' 


, , * *rj 


, , 


-37- 


Figure  32. 
Figure  33. 


Figure  34. 


Figure  35. 


Pharynx  in  cross-section,  x 128 
Cross-section  of  the  "body  in  the  region 
of  the  oo type,  x 41 
oo t.  oo type 
s.  g.  shell  gland 
y.d.  yolk  duct 

Cross-section  of  the  body  in  the  region 
of  the  receptaculum  seminale.  x 41 
d. cr.  digestive  crus 
ov.  ovary 

r.s.  receptaculum  seminale 
vit.  vitellaria 

Excretory  duct  in  cross-section,  and 
external  orifice,  x 238. 


/ 


> . 


